Disturbance-mediated competition between perennial plants along a resource supply gradient

Abstract

1.Traditional views of ecological disturbance emphasize the role that physical disturbances play in reducing competition between populations and maintaining species coexistence. I present an alternative view that employs a simple Lotka-Volterra model to demonstrate how disturbance resistance, disturbance resilience and resource storage can increase competition between individual perennial plants of similar growth form along a resource supply gradient. 2.In contrasting the growth of individual genets of two hypothetical species, I assumed that traits associated with inherently low module (i.e. plant part) mortality in infertile soils resulted in greater resource storage, but traded off with maximum potential net photosynthesis rates and thus disturbance resilience. 3.The species with more persistent modules (the 'persistent' species) and greater storage produced larger genets and displaced the other species at low gross resource supplies as a result of pre-emption. 4.The species with the greater net photosynthesis rate (the 'resilient' species) gained a size and competitive advantage with increasing gross resource supply, provided senescence of its modules was sufficiently low or there was a constant and equivalent rate of damage to portions of the genets of both species. 5.Selection for disturbance resistance was greater in the persistent species than in the resilient species, which in turn increased the former's competitive ability in moderately resource-rich, disturbance-prone environments. 6.Synthesis. Both resistance and resilience to disturbance potentially increase a species' competitive ability by allowing that species to interfere with the recovery of its competitors from disturbance. Contrary to the view that disturbances must be eliminated from competition experiments to accurately measure the potential for competition to structure plant communities, I conclude that the opposite is true. © 2011 The Author. Journal of Ecology © 2011 British Ecological Society.